I assume that you mean AIX 7.2 ??
You can send HTML emails using sendmail, but it may depend how your email has been configured.
There are different ways to do this, but here is a test script that works for me.
It uses old school HTML, but don't judge me!
TMP_MAILFILE=/tmp/myfile
MAILTO=<email_address_here>
REPLY=<email_address_here>
FROM=<email_address_here>
SUBJECT="Test Email"
echo "Reply-To: ${REPLY}" >> ${TMP_MAILFILE}
echo "From: ${FROM}" >> ${TMP_MAILFILE}
echo "Subject: $SUBJECT" >> ${TMP_MAILFILE}
echo "MIME-Version: 1.0" >> ${TMP_MAILFILE}
echo "Content-Type: text/html" >> ${TMP_MAILFILE}
echo "Content-Disposition: inline" >> ${TMP_MAILFILE}
echo "<HTML>" >> ${TMP_MAILFILE}
echo "<HEAD>" >> ${TMP_MAILFILE}
echo "<style type='text/css'>" >> ${TMP_MAILFILE}
echo "body" >> ${TMP_MAILFILE}
echo "{" >> ${TMP_MAILFILE}
echo "font-family:'Arial';" >> ${TMP_MAILFILE}
echo "font-size:10pt;" >> ${TMP_MAILFILE}
echo "}" >> ${TMP_MAILFILE}
echo "</HEAD>" >> ${TMP_MAILFILE}
echo "<BODY>" >> ${TMP_MAILFILE}
echo "An HTML Email<BR>" >> ${TMP_MAILFILE}
echo "<BR>" >> ${TMP_MAILFILE}
echo "Some text" >> ${TMP_MAILFILE}
echo "<BR>" >> ${TMP_MAILFILE}
echo "<BR>" >> ${TMP_MAILFILE}
echo "<TABLE BORDER=1 BGCOLOR=Cornsilk>" >> ${TMP_MAILFILE}
echo "<TR><TH COLSPAN=2 BGCOLOR=SkyBlue>My HTML Table</TH></TR>" >> ${TMP_MAILFILE}
echo "<TR>" >> ${TMP_MAILFILE}
echo "<TH WIDTH=100 ALIGN=LEFT BGCOLOR=PowderBlue>Column 1</TH>" >> ${TMP_MAILFILE}
echo "<TH WIDTH=80 ALIGN=LEFT BGCOLOR=PowderBlue>Column 2</TH>" >> ${TMP_MAILFILE}
echo "</TR>" >> ${TMP_MAILFILE}
echo "<TR>" >> ${TMP_MAILFILE}
echo "<TD ALIGN=LEFT>Val 1.1</TD>" >> ${TMP_MAILFILE}
echo "<TD ALIGN=LEFT>Val 1.2</TD>" >> ${TMP_MAILFILE}
echo "</TR>" >> ${TMP_MAILFILE}
echo "<TR>" >> ${TMP_MAILFILE}
echo "<TD ALIGN=LEFT>Val 2.1</TD>" >> ${TMP_MAILFILE}
echo "<TD ALIGN=LEFT>Val 2.2</TD>" >> ${TMP_MAILFILE}
echo "</TR>" >> ${TMP_MAILFILE}
echo "</TABLE>" >> ${TMP_MAILFILE}
echo "<BR>" >> ${TMP_MAILFILE}
echo '</BODY></HTML>' >> ${TMP_MAILFILE}
echo "Sending email..."
cat ${TMP_MAILFILE} | /usr/sbin/sendmail -f ${FROM} ${MAILTO}
------------------------------
Mike Walker
xDB Systems, Inc
www.xdbsystems.com------------------------------